|Publication number||US7574584 B2|
|Application number||US 11/186,239|
|Publication date||Aug 11, 2009|
|Filing date||Jul 21, 2005|
|Priority date||Jul 27, 2004|
|Also published as||EP1622009A1, US7260682, US7493476, US7500085, US7533250, US7543285, US7546437, US7587583, US7606977, US7624382, US7743384, US7752610, US7757223, US7930689, US8024554, US8024716, US8046748, US8078842, US8185666, US8380906, US8516496, US9201807, US20060023517, US20060025986, US20060026126, US20060026183, US20060026200, US20060026201, US20060026312, US20060026322, US20060026353, US20060026354, US20060026357, US20060026370, US20060026390, US20060026391, US20060026392, US20060026393, US20060026394, US20060026395, US20060026396, US20060026397, US20060026398, US20060026400, US20060026401, US20060026402, US20060026403, US20060026404, US20060026405, US20060026407, US20060026412, US20060026563, US20060026564, US20060026565, US20060026566, US20060026571, US20060026574, US20060026575, US20060026580|
|Publication number||11186239, 186239, US 7574584 B2, US 7574584B2, US-B2-7574584, US7574584 B2, US7574584B2|
|Inventors||Gerard Chauvel, Maija Kuusela|
|Original Assignee||Texas Instruments Incorporated|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Classifications (12), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application claims priority to European Patent Application No. 04291918.3, filed Jul. 27, 2004, and which is incorporated by reference herein as if reproduced in full below.
1. Technical Field
The present subject matter relates generally to processors and more particularly to splitting the execution of instructions (e.g., floating point instructions) between hardware and software.
2. Background Information
Many types of electronic devices are battery operated and thus preferably consume as little power as possible. An example is a cellular telephone. Further, it may be desirable to implement various types of multimedia functionality in an electronic device such as a cell phone. Examples of multimedia functionality may include, without limitation, games, audio decoders, digital cameras, etc. It is thus desirable to implement such functionality in an electronic device in a way that, all else being equal, is fast, consumes as little power as possible and/or requires as little memory as possible. Improvements in this area are desirable.
In some embodiments, a processor comprises fetch logic that fetches instructions, an integer pipeline, and a hardware state machine that is separate from and interacts with the integer pipeline. The instruction is executed partly in the integer pipeline according to software and partly in the hardware state machine. Another embodiment comprises a method that includes fetching an instruction, executing the instruction partially in a hardware state machine; and executing the instruction partially in an integer pipeline.
Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, semiconductor companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. The term “system” refers broadly to a collection of two or more components and may be used to refer to an overall system (e.g., a communication system such as a cellular telephone) as well as a subsystem (e.g., a processor) provided as part of a larger system.
For a more detailed description of the preferred embodiments of the present invention, reference will now be made to the accompanying drawings, wherein:
The following discussion is directed to various embodiments of the invention. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims, unless otherwise specified. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.
Various values are passed from the hardware 54 to the software 56 and vice versa as desired to execute the instruction. The instruction initiates a series of concurrent, mutually coordinated operations in the hardware 54 and in software 56 to at least partially execute the instruction. In this manner (coordinated interaction between hardware and software), an instruction may be executed more cost efficiently but still preserving satisfactory performance than if the instruction was executed exclusively in software or exclusively in hardware. Any of a variety of instructions can be split between hardware and software. Examples include floating point multiply instructions, floating point add instructions, floating point-to-integer conversion instructions, integer-to-floating point conversion instructions, and floating point compare instructions.
In at least some embodiments, one or more instructions are executed by a programmable electronic device such as a processor. The processor described herein is particularly suited for executing Java™ Bytecodes or comparable code. As is well known, Java is particularly suited for embedded applications. Java is a relatively “dense” language meaning that on average each instruction may perform a large number of functions compared to various other programming languages. The dense nature of Java is of particular benefit for portable, battery-operated devices that preferably include as little memory as possible to save space and power. The reason, however, for executing Java code is not material to this disclosure or the claims which follow. Further, the processor advantageously includes one or more features that permit the execution of the Java code to be accelerated.
The processor may, for example, be incorporated into a portable, battery-operated, communication device (e.g., a cellular telephone) such as that shown in
Referring now to
As is generally well known, Java code comprises a plurality of “bytecodes” 112. Some bytecodes may be integer bytecodes and other bytecodes may be floating point bytecodes. Bytecodes 112 may be provided to the JVM 108, compiled by compiler 110 and provided to the JSM 102 and/or MPU 104 for execution therein. In accordance with a preferred embodiment of the invention, the JSM 102 may execute at least some, and generally most, of the Java bytecodes. When appropriate, however, the JSM 102 may request the MPU 104 to execute one or more Java bytecodes not executed or executable by the JSM 102. In addition to executing Java bytecodes, the MPU 104 also may execute non-Java instructions. The MPU 104 also hosts an operating system (“O/S”) (not specifically shown) which performs various functions including system memory management, the system task management that schedules the JVM 108 and most or all other native tasks running on the system, management of the display 114, receiving input from input devices, etc. Without limitation, Java code may be used to perform any one of a variety of applications including multimedia, games or web based applications in the system 100, while non-Java code, which may comprise the O/S and other native applications, may still run on the system on the MPU 104.
The JVM 108 is generally coupled to the compiler 110 and the JSM 102. Functionally, the JVM may include a class loader, bytecode verifier, garbage collector, and a bytecode interpreter loop to interpret the bytecodes that are not executed on the JSM processor 102.
Referring now to
Referring again to
The integer pipeline 149 executes at least a portion of an instruction in software. The ALU 148 of the integer pipeline adds, subtracts, and shifts data. The multiplier 150 may be used to multiply two values together in one or more cycles. The instruction fetch logic 154 generally fetches instructions from instruction storage 130. The instructions may be decoded by decode logic 152.
The data storage 122 generally comprise data cache (“D-cache”) 124 anddata random access memory (“D-RAMset”) 126. Reference may be made to copending applications U.S. Ser. No. 09/591,537 filed Jun. 9, 2000, Ser. No. 09/591,656 filed Jun. 9, 2000, and Ser. No. 09/932,794 filed Aug. 17, 2001, all of which are incorporated herein by reference. The stack (excluding the micro-stack 146), arrays and non-critical data may be stored in the D-cache 124, while Java local variables, critical data and non-Java variables (e.g., C, C++) may be stored in D-RAM 126. The instruction storage 130 may comprise instruction RAM (“I-RAM”) 132 and instruction cache (“I-cache”) 134. The I-RAM 132 may be used for various instruction sequences that are executed in place of, for example, a Java bytecode. The I-cache 134 may be used to store other types of Java bytecode and mixed Java/other instructions. Error handlers may also be stored in and executed from the I-RAM 132 and/or I-cache 134.
The data storage 122 generally comprises data cache (“D-cache”) 124 and data random access memory (“D-RAMset”) 126. Reference may be made to copending applications U.S. Ser. No. 09/591,537 filed Jun. 9, 2000, now U.S. Pat. No. 6,826,652, granted Nov. 30, 2004, Ser. No. 09/591,656 filed Jun. 9, 2000, now U.S. Pat. No. 6,792,508, granted Sep. 14, 2004, and Ser. No. 09/932,794 filed Aug. 17, 2001, now U.S. Pat. No. 6,789,172, granted Sep. 7, 2004, all of which are incorporated herein by reference. The stack (excluding the micro-stack 146), arrays and non-critical data may be stored in the D-cache 124, while Java local variables, critical data and non-Java variables (e.g., C, C++) may be stored in D-RAM 126. The instruction storage 130 may comprise instruction RAM (“I-RAM”) 132 and instruction cache (“I-cache”) 134. The I-RAM 132 may be used for various instruction sequences that are executed in place of, for example, a Java bytecode. The I-cache 134 may be used to store other types of Java bytecode and mixed Java/other instructions. Error handlers may also be stored in and executed from the I-RAM 132 and/or I-cache 134.
The hardware state machine 151 also comprises overflow logic comprising logic blocks 210 and 212. Overflow logic 210 detects the situation where rounding up may cause the result to overflow, while overflow logic 212 detects the situation where overflow is certain independently of the rounding. The test logic 200 and the test logic 202 indicate exceptional cases where the parallel hardware-software execution mode is abandoned and the execution continues with pure software exception handler 250 or 252. This is an advantageous way of dealing with the cases where denormalized arguments or denormalized result requires a variable-sized shift to be performed.
The hardware state machine 151 also contains pack logic comprising multiplexer 214, adder 218, which may be physically the same adder as 206, and pack logic unit 216. Such hardware blocks form the final result by packing the sign, mantissa and exponent information computed in the previous cycles into a single 32-bit word. Logic 220 comprises rounding logic that detects the need for rounding up. Register 222 represents the final floating point answer before rounding.
The integer pipeline 149 interacts with and is synchronized to the hardware state machine 151. The operation of the logic depicted in
While the preferred embodiments of the present invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited by the description set out above. Each and every claim is incorporated into the specification as an embodiment of the present invention.
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|U.S. Classification||712/222, 708/505|
|International Classification||G06F7/42, G06F9/00|
|Cooperative Classification||G06F9/45504, G06F9/30174, G06F12/0802, G06F2212/6012, G06F12/1081, Y02B60/1225|
|European Classification||G06F9/30U2, G06F12/10P|
|Jul 21, 2005||AS||Assignment|
Owner name: TEXAS INSTRUMENTS INCORPORATED, TEXAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CHAUVEL, GERARD;KUUSELA, MAIJA;REEL/FRAME:016802/0022
Effective date: 20050610
|Sep 7, 2010||CC||Certificate of correction|
|Jan 25, 2013||FPAY||Fee payment|
Year of fee payment: 4